Abstract The gas phase nucleation process of anatase TiO2 in atmospheric non-thermal plasma enhanced chemical vapor deposition is studied. The particles synthesized in the plasma gas phase at different power density w...Abstract The gas phase nucleation process of anatase TiO2 in atmospheric non-thermal plasma enhanced chemical vapor deposition is studied. The particles synthesized in the plasma gas phase at different power density were collected outside of the reactor. The structure of the collected particles has been investigated by field scanning electron microscope （FESEM）, X-ray diffraction （XRD）, high resolution transmission electron microscopy （HRTEM） and selected area electron diffraction （SAED）. The analysis shows that uniform crystalline nuclei with average size of several nanometers have been formed in the scale of micro second through this reactive atmo- spheric plasma gas process. The crystallinity of the nanoparticles increases with power density. The high density of crystalline nanonuclei in the plasma gas phase and the low gas temperature are beneficial to the fast deposition of the 3D porous anatase TiO2 film.展开更多
Oxygen vacancies have a profound effect on the magnetic,electronic,and transport properties of transition metal oxides but little is known about their effect on thermal expansion.Herein we report the effect of oxygen ...Oxygen vacancies have a profound effect on the magnetic,electronic,and transport properties of transition metal oxides but little is known about their effect on thermal expansion.Herein we report the effect of oxygen defects on the structure formation and thermal expansion properties of the layered perovskite Ca2RuO4(CRO).It is shown that the CRO containing excess oxygen crystallizes in a metallic L-CRO phase without structure transition from 100 K to 500 K and displays a normal thermal expansion behavior,whereas those with oxygen vacancies adopt at room temperature an insulating S-CRO phase and exhibit an enormous negative thermal expansion(NTE)from 100 K to about 360 K,from where they undergo a structure transition to a high temperature metallic L-CRO phase.Compared to the L-CRO containing excess oxygen,the S-CRO structure has increasingly large orthorhombic strain and distinctive in-plane distortion upon cooling.The in-plane distortion of the RuO6 octahedra reaches a maximum across 260 K and then relaxes monotonically,providing a structure evidence for the appearance of an antiferromagnetic orbital ordering in the paramagnetic phase and the A_g phonon mode suppression and phase flip across the same temperature found recently.Both the L-and S-CRO display an antiferromagnetic ordering at about 150-110 K,with ferromagnetic ordering components at lower temperature.The NTE in S-CRO is a result of a complex interplay among the spin,orbital,and lattice.展开更多
In this paper,polyimide（PI）films are modified using an atmospheric pressure plasma generated by a dielectric barrier discharge（DBD）in argon.Surface performance of PI film and its dependence on exposure time from 0...In this paper,polyimide（PI）films are modified using an atmospheric pressure plasma generated by a dielectric barrier discharge（DBD）in argon.Surface performance of PI film and its dependence on exposure time from 0 s to 300 s are investigated by dynamic water contact angle（WCA）,field emission scanning electron microscopy（FESEM）,and Fourier transform infrared spectroscopy in attenuated total multiple reflection mode（FTIR-ATR）.The study demonstrates that dynamic WCA exhibits a minimum with 40 s plasma treatment,and evenly distributed nano-dots and shadow concaves appeared for 40 s and 12 s Ar plasma treatment individually.A short period of plasma modification can contribute to the scission of the imide ring and the introduction of C-O and C=O（-COOH）by detailed analysis of FTIR-ATR.展开更多
Electronic properties of both Pb and S vacancy defects in PbS（1^-00） have been studied using the first-principles density functional theory （DFT） calculations with the plane-wave pseudopotentials. It is found that...Electronic properties of both Pb and S vacancy defects in PbS（1^-00） have been studied using the first-principles density functional theory （DFT） calculations with the plane-wave pseudopotentials. It is found that the density of states （DOS） near the top of the valence band and the bottom of the conduction band is significantly modified by these defects. Our calculation indicates that in the case of S vacancy defects the Fermi energy shifts to the conduction band making it as an n-type PbS （donor）. However, in the case of Pb vacancy, because of the appreciable change of the DOS, the system acts as a p-type PbS （accepter）. In addition, the structural relaxation shows that the defect leads to outward relaxation of the nearest-neighbouring atoms and inward relaxation of the next-nearest neighbouring atoms.展开更多
A method, the morphology of screen printed carbon nanotube pastes is modified using a hard hairbrush, is presented. In this way, the organic matrix material is preferentially removed. Compared to those untreated films...A method, the morphology of screen printed carbon nanotube pastes is modified using a hard hairbrush, is presented. In this way, the organic matrix material is preferentially removed. Compared to those untreated films, the turn-on electric field of the treated film decreases from 2.2V/μm to 1.6V/μm, while the total emission current of the treated increases from 0.6mA/cm2 to 3mA/cm2, and uniform emission site density image has also been observed.展开更多
A solid solution of （HfSc）0.83W2.25P0.83O12-δ is synthesized by the high-temperature, solid-state reaction and fast-quenching method. It is shown that it possesses an orthorhombic structure with space group Pmmm ...A solid solution of （HfSc）0.83W2.25P0.83O12-δ is synthesized by the high-temperature, solid-state reaction and fast-quenching method. It is shown that it possesses an orthorhombic structure with space group Pmmm （47） and exhibits negative thermal expansion （NTE） property with low anisotropy in thermal expansion. The coefficients of thermal expansion （CTEs） for a, b, and c axes are -1.41×10^-6 K^-1, -2.23×10^-6 K^-1, and -1.87×10^-6 K^-1, respectively. This gives rise to volume and linear CTEs of -3.10×10^-6 K^-1 and -1.03×10^-6 K^-1, respectively. Besides, it exhibits also intense photoluminescence from 360 nm to about 600 nm. The mechanism of NTE and the correlation of the PL with axial thermal expansion property are discussed.展开更多
We investigate the dc Josephson effect in one-dimensional junctions where a ring conductor is sandwiched between two semiconductor nanowires with proximity-induced superconductivity. Peculiar features of the Josephson...We investigate the dc Josephson effect in one-dimensional junctions where a ring conductor is sandwiched between two semiconductor nanowires with proximity-induced superconductivity. Peculiar features of the Josephson effect arise due to the interplay of spin-orbit interaction and external Zeenmn field. By tuning the Zeeman field orientation, the device can vary from 0 to π junction. Afore importantly, nonzero ,losephson current is possible at zero phase difference across the junction. Although this anomalous Josephson current is not relevant to the topological phase transition, its magnitude can be significantly enhanced whe, n the nanowire, s become topological superconductors where Majorana bound states emerge. Distinct modulation patterns are obtained for the semiconductor nanowires in the topologically trivial and non-trivial phases. These results are useful to probe the topological phase transition in semiconductor nanowire junctions via the dc Josephson effect.展开更多
We investigate the transport properties of a pair of Majorana bound states in a T-shaped junction, where two normal leads are coupled with an identical Majorana bound state. Both the scattering matrix and the recursiv...We investigate the transport properties of a pair of Majorana bound states in a T-shaped junction, where two normal leads are coupled with an identical Majorana bound state. Both the scattering matrix and the recursive Green function method show that the peak value of the differential conductance （Gpeak） in units of e2/h and the shot noise Fano factor in the zero bias limit （F0）, which are measured at the same lead and zero temperature, satisfy a linear relation as F0=1＋Gpeak/2, independent of the magnitude or symmetry of the coupling strengths to the leads. Therefore, combined measurements of the differential conductance and shot noise in the T-shaped geometry can serve as a characteristic signature in probing Majorana bound states.展开更多
Manganese oxides with a perovskite-type Re_(1-x)D_xMnO_3(Re:heavy rare-earth elements,D:divalent alkali metal)structure have attracted interest because of the complex interaction between their electrons,lattices,and s...Manganese oxides with a perovskite-type Re_(1-x)D_xMnO_3(Re:heavy rare-earth elements,D:divalent alkali metal)structure have attracted interest because of the complex interaction between their electrons,lattices,and spins[1-5].Generally,manganese oxides with the structure Re_(1-x)D_xMnO_3 have special properties.For example,the half-metallic manganites,such as La_(2/3)Sr_(1/3)MnO_3 and La_(2/3)Ca_(1/3)MnO_3,wherein the conduction electrons are completely spin polarized。展开更多
A novel post-treatment method, including hard hairbrush and electrical treatment, is performed intentionally to improve the field emission capability and stability of screen-printed carbon nanotubes （CNTs）. Compared...A novel post-treatment method, including hard hairbrush and electrical treatment, is performed intentionally to improve the field emission capability and stability of screen-printed carbon nanotubes （CNTs）. Compared with untreated films, the field emission properties of the treated ones are greatly enhanced. Scanning electron microscopy （SEM） and Raman spectrum studies reveal that field emission properties are enhanced by two factors. Firstly, the improved field emission properties of CNT films can be attributed to the more active CNT surface by removing the organic material cover on the CNTs. Secondly, the gener- ation of a high density of structural defects and the lower resistance contact to the topside CNT emitters after treatment are all helpful to improving the field emission properties of the treated CNTs.展开更多
The advent of low-dimensional materials with peculiar structure and superb band properties provides a new canonical form for the development of photodetectors.However,the limited exploitation of basic properties makes...The advent of low-dimensional materials with peculiar structure and superb band properties provides a new canonical form for the development of photodetectors.However,the limited exploitation of basic properties makes it difficult for devices to stand out.Here,we demonstrate a hybrid heterostructure with ultrathin vanadium dioxide film and molybdenum ditelluride nanoflake.Vanadium dioxide is a classical semiconductor with a narrow bandgap,a high temperature coefficient of resistance,and phase transformation.Molybdenum ditelluride,a typical two-dimensional material,is often used to construct optoelectronic devices.The heterostructure can realize three different functional modes:(i)the p-n junction exhibits ultrasensitive detection(450 nm-2μm)with a dark current down to 0.2 pA and a response time of 17μs,(ii)the Schottky junction works stably under extreme conditions such as a high temperature of 400 K,and(iii)the bolometer shows ultrabroad spectrum detection exceeding 10μm.The flexible switching between the three modes makes the heterostructure a potential candidate for next-generation photodetectors from visible to longwave infrared radiation(LWIR).This type of photodetector combines versatile detection modes,shedding light on the hybrid application of novel and traditional materials,and is a prototype of advanced optoelectronic devices.展开更多
The enhancement of energy density and cycling stability is in urgent need for the widespread applications of aqueous rechargeable Ni-Zn batteries.Herein,a facile strategy has been employed to construct hierarchical Co...The enhancement of energy density and cycling stability is in urgent need for the widespread applications of aqueous rechargeable Ni-Zn batteries.Herein,a facile strategy has been employed to construct hierarchical Co-doped NiMoO4nanosheets as the cathode for high-performance Ni-Zn battery.Benefiting from the merits of substantially improved electrical conductivity and increased concentration of oxygen vacancies,the NiMoO4with 15%cobalt doping(denoted as CNMO-15)displays the best capacity of 361.4 m A h g-1at a current density of 3 A g-1and excellent cycle stability.Moreover,the assembled CNMO-15//Zn battery delivers a satisfactory specific capacity of 270.9 mA h g-1at 2 A g-1and a remarkable energy density of 474.1 W h kg-1at 3.5 kW kg-1,together with a maximum power density of 10.3 kW kg-1achieved at 118.8 W h kg-1.Noticeably,there is no capacity decay with a 119.8%retention observed after 5000 cycles,demonstrating its outstanding long lifespan.This work might provide valuable inspirations for the fabrication of high-performance Ni-Zn batteries with superior energy density and impressive stability.展开更多
Many attempts have been made to standardize the calculation of whiteness. Whiteness formulas currently in use satisfactorily characterize the appearance of commercial whiteness. However, they have poor correlations wi...Many attempts have been made to standardize the calculation of whiteness. Whiteness formulas currently in use satisfactorily characterize the appearance of commercial whiteness. However, they have poor correlations with the observers＇ evaluations, and are often unsuccessful in assessing tinted white samples. A whiteness formula in the CIELAB uniform color space is developed in this paper. Several whiteness formulas are analyzed and compared. The experimental results show that the whiteness formula in the CIELAB uniform color space agrees well with the visual ranking, and it is superior to the CIE whiteness formula and the others in visual correlativity, uniformity and applicability.展开更多
基金supported by National Natural Science Foundation of China(Nos.1083500410775031 and 11375042)+1 种基金Shanghai Municipal Committee of Science and Technology of China(10XD1400100)Outstanding Young Investigator Award(No.11005017)
文摘Abstract The gas phase nucleation process of anatase TiO2 in atmospheric non-thermal plasma enhanced chemical vapor deposition is studied. The particles synthesized in the plasma gas phase at different power density were collected outside of the reactor. The structure of the collected particles has been investigated by field scanning electron microscope （FESEM）, X-ray diffraction （XRD）, high resolution transmission electron microscopy （HRTEM） and selected area electron diffraction （SAED）. The analysis shows that uniform crystalline nuclei with average size of several nanometers have been formed in the scale of micro second through this reactive atmo- spheric plasma gas process. The crystallinity of the nanoparticles increases with power density. The high density of crystalline nanonuclei in the plasma gas phase and the low gas temperature are beneficial to the fast deposition of the 3D porous anatase TiO2 film.
基金the National Natural Science Foundation of China(Grant Nos.11874328 and 11574276)The SXRD experiments were performed at the BL02B2 and BL04B2 of SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute(JASRI+1 种基金proposal Nos.2019A1167,2019A1095,and 2019A1340)We also acknowledge the help of Beamline Scientists Dr.Lirong Zheng(BSRF),Dr.Shogo Kawaguchi,and Dr.Koji Ohara(SPring-8).
文摘Oxygen vacancies have a profound effect on the magnetic,electronic,and transport properties of transition metal oxides but little is known about their effect on thermal expansion.Herein we report the effect of oxygen defects on the structure formation and thermal expansion properties of the layered perovskite Ca2RuO4(CRO).It is shown that the CRO containing excess oxygen crystallizes in a metallic L-CRO phase without structure transition from 100 K to 500 K and displays a normal thermal expansion behavior,whereas those with oxygen vacancies adopt at room temperature an insulating S-CRO phase and exhibit an enormous negative thermal expansion(NTE)from 100 K to about 360 K,from where they undergo a structure transition to a high temperature metallic L-CRO phase.Compared to the L-CRO containing excess oxygen,the S-CRO structure has increasingly large orthorhombic strain and distinctive in-plane distortion upon cooling.The in-plane distortion of the RuO6 octahedra reaches a maximum across 260 K and then relaxes monotonically,providing a structure evidence for the appearance of an antiferromagnetic orbital ordering in the paramagnetic phase and the A_g phonon mode suppression and phase flip across the same temperature found recently.Both the L-and S-CRO display an antiferromagnetic ordering at about 150-110 K,with ferromagnetic ordering components at lower temperature.The NTE in S-CRO is a result of a complex interplay among the spin,orbital,and lattice.
文摘In this paper,polyimide（PI）films are modified using an atmospheric pressure plasma generated by a dielectric barrier discharge（DBD）in argon.Surface performance of PI film and its dependence on exposure time from 0 s to 300 s are investigated by dynamic water contact angle（WCA）,field emission scanning electron microscopy（FESEM）,and Fourier transform infrared spectroscopy in attenuated total multiple reflection mode（FTIR-ATR）.The study demonstrates that dynamic WCA exhibits a minimum with 40 s plasma treatment,and evenly distributed nano-dots and shadow concaves appeared for 40 s and 12 s Ar plasma treatment individually.A short period of plasma modification can contribute to the scission of the imide ring and the introduction of C-O and C=O（-COOH）by detailed analysis of FTIR-ATR.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60476040, 60221502 and 60571021, and the Knowledge Innovation Project of Chinese Academy of Sciences under Grant No C2-5.
文摘Electronic properties of both Pb and S vacancy defects in PbS（1^-00） have been studied using the first-principles density functional theory （DFT） calculations with the plane-wave pseudopotentials. It is found that the density of states （DOS） near the top of the valence band and the bottom of the conduction band is significantly modified by these defects. Our calculation indicates that in the case of S vacancy defects the Fermi energy shifts to the conduction band making it as an n-type PbS （donor）. However, in the case of Pb vacancy, because of the appreciable change of the DOS, the system acts as a p-type PbS （accepter）. In addition, the structural relaxation shows that the defect leads to outward relaxation of the nearest-neighbouring atoms and inward relaxation of the next-nearest neighbouring atoms.
文摘A method, the morphology of screen printed carbon nanotube pastes is modified using a hard hairbrush, is presented. In this way, the organic matrix material is preferentially removed. Compared to those untreated films, the turn-on electric field of the treated film decreases from 2.2V/μm to 1.6V/μm, while the total emission current of the treated increases from 0.6mA/cm2 to 3mA/cm2, and uniform emission site density image has also been observed.
基金supported by the National Natural Science Foundation of China(Grant Nos.11574276,51302249,and 11405028)the Fundamental Research Fund for the Central Universities,China
文摘A solid solution of （HfSc）0.83W2.25P0.83O12-δ is synthesized by the high-temperature, solid-state reaction and fast-quenching method. It is shown that it possesses an orthorhombic structure with space group Pmmm （47） and exhibits negative thermal expansion （NTE） property with low anisotropy in thermal expansion. The coefficients of thermal expansion （CTEs） for a, b, and c axes are -1.41×10^-6 K^-1, -2.23×10^-6 K^-1, and -1.87×10^-6 K^-1, respectively. This gives rise to volume and linear CTEs of -3.10×10^-6 K^-1 and -1.03×10^-6 K^-1, respectively. Besides, it exhibits also intense photoluminescence from 360 nm to about 600 nm. The mechanism of NTE and the correlation of the PL with axial thermal expansion property are discussed.
基金Supported by the Fundamental Research Funds for the Central Universities under Grant No 15D210901the National Natural Science Foundation of China under Grant Nos 11174049 and 61290301the National University Student Innovation Program under Grant No 14T10902
文摘We investigate the dc Josephson effect in one-dimensional junctions where a ring conductor is sandwiched between two semiconductor nanowires with proximity-induced superconductivity. Peculiar features of the Josephson effect arise due to the interplay of spin-orbit interaction and external Zeenmn field. By tuning the Zeeman field orientation, the device can vary from 0 to π junction. Afore importantly, nonzero ,losephson current is possible at zero phase difference across the junction. Although this anomalous Josephson current is not relevant to the topological phase transition, its magnitude can be significantly enhanced whe, n the nanowire, s become topological superconductors where Majorana bound states emerge. Distinct modulation patterns are obtained for the semiconductor nanowires in the topologically trivial and non-trivial phases. These results are useful to probe the topological phase transition in semiconductor nanowire junctions via the dc Josephson effect.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11074266, 11174049 and 61376017, the Fundamental Research Funds for the Central Universities, the Natural Science Foundation of Liaoning Province under Grant No 2013020030, and the Liaoning BaiQianWan Talents Program under Grant No 2012921078.
文摘We investigate the transport properties of a pair of Majorana bound states in a T-shaped junction, where two normal leads are coupled with an identical Majorana bound state. Both the scattering matrix and the recursive Green function method show that the peak value of the differential conductance （Gpeak） in units of e2/h and the shot noise Fano factor in the zero bias limit （F0）, which are measured at the same lead and zero temperature, satisfy a linear relation as F0=1＋Gpeak/2, independent of the magnitude or symmetry of the coupling strengths to the leads. Therefore, combined measurements of the differential conductance and shot noise in the T-shaped geometry can serve as a characteristic signature in probing Majorana bound states.
基金supported by the Major State Basic Research Development Program(Grant No.2013CB922302)the National Natural Science Foundation of China(Grant No.11374320)
文摘Manganese oxides with a perovskite-type Re_(1-x)D_xMnO_3(Re:heavy rare-earth elements,D:divalent alkali metal)structure have attracted interest because of the complex interaction between their electrons,lattices,and spins[1-5].Generally,manganese oxides with the structure Re_(1-x)D_xMnO_3 have special properties.For example,the half-metallic manganites,such as La_(2/3)Sr_(1/3)MnO_3 and La_(2/3)Ca_(1/3)MnO_3,wherein the conduction electrons are completely spin polarized。
文摘A novel post-treatment method, including hard hairbrush and electrical treatment, is performed intentionally to improve the field emission capability and stability of screen-printed carbon nanotubes （CNTs）. Compared with untreated films, the field emission properties of the treated ones are greatly enhanced. Scanning electron microscopy （SEM） and Raman spectrum studies reveal that field emission properties are enhanced by two factors. Firstly, the improved field emission properties of CNT films can be attributed to the more active CNT surface by removing the organic material cover on the CNTs. Secondly, the gener- ation of a high density of structural defects and the lower resistance contact to the topside CNT emitters after treatment are all helpful to improving the field emission properties of the treated CNTs.
基金supported by the Natural Science Foundation of China(Grant Nos.61835012,61722408,61725505,61521005,and 61905267)the Key Research Project of Frontier Sciences of the Chinese Academy of Sciences(Grant Nos.QYZDB-SSW-JSC016 and QYZDY-SSW-JSC042)+4 种基金the Key Research Program of Frontier Science,CAS(Grant No.ZDBS-LY-JSC045)the Major State Basic Research Development Program(Grant No.2016YFA0203900)the National Postdoctoral Program for Innovative Talents(BX20180329)the Natural Science Foundation of Shanghai(Grant Nos.16ZR1447600 and 17JC1400302)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB44000000).
文摘The advent of low-dimensional materials with peculiar structure and superb band properties provides a new canonical form for the development of photodetectors.However,the limited exploitation of basic properties makes it difficult for devices to stand out.Here,we demonstrate a hybrid heterostructure with ultrathin vanadium dioxide film and molybdenum ditelluride nanoflake.Vanadium dioxide is a classical semiconductor with a narrow bandgap,a high temperature coefficient of resistance,and phase transformation.Molybdenum ditelluride,a typical two-dimensional material,is often used to construct optoelectronic devices.The heterostructure can realize three different functional modes:(i)the p-n junction exhibits ultrasensitive detection(450 nm-2μm)with a dark current down to 0.2 pA and a response time of 17μs,(ii)the Schottky junction works stably under extreme conditions such as a high temperature of 400 K,and(iii)the bolometer shows ultrabroad spectrum detection exceeding 10μm.The flexible switching between the three modes makes the heterostructure a potential candidate for next-generation photodetectors from visible to longwave infrared radiation(LWIR).This type of photodetector combines versatile detection modes,shedding light on the hybrid application of novel and traditional materials,and is a prototype of advanced optoelectronic devices.
基金financially supported by the National Natural Science Foundation of China(51602049)the Fundamental Research Funds for the Central Universities(2232017D-15,GSIF-DH-M-2020002)China Postdoctoral Science Foundation(2017M610217 and 2018T110322)。
文摘The enhancement of energy density and cycling stability is in urgent need for the widespread applications of aqueous rechargeable Ni-Zn batteries.Herein,a facile strategy has been employed to construct hierarchical Co-doped NiMoO4nanosheets as the cathode for high-performance Ni-Zn battery.Benefiting from the merits of substantially improved electrical conductivity and increased concentration of oxygen vacancies,the NiMoO4with 15%cobalt doping(denoted as CNMO-15)displays the best capacity of 361.4 m A h g-1at a current density of 3 A g-1and excellent cycle stability.Moreover,the assembled CNMO-15//Zn battery delivers a satisfactory specific capacity of 270.9 mA h g-1at 2 A g-1and a remarkable energy density of 474.1 W h kg-1at 3.5 kW kg-1,together with a maximum power density of 10.3 kW kg-1achieved at 118.8 W h kg-1.Noticeably,there is no capacity decay with a 119.8%retention observed after 5000 cycles,demonstrating its outstanding long lifespan.This work might provide valuable inspirations for the fabrication of high-performance Ni-Zn batteries with superior energy density and impressive stability.
文摘Many attempts have been made to standardize the calculation of whiteness. Whiteness formulas currently in use satisfactorily characterize the appearance of commercial whiteness. However, they have poor correlations with the observers＇ evaluations, and are often unsuccessful in assessing tinted white samples. A whiteness formula in the CIELAB uniform color space is developed in this paper. Several whiteness formulas are analyzed and compared. The experimental results show that the whiteness formula in the CIELAB uniform color space agrees well with the visual ranking, and it is superior to the CIE whiteness formula and the others in visual correlativity, uniformity and applicability.
